Abstract: The use of magnesium alloys is limited due to their
susceptibility to corrosion although they have many attractive
physical and mechanical properties. To increase mechanical and
corrosion properties of these alloys, many deposition method and
coating types are used. Electroless Ni–B coatings have received
considerable interest recently due to its unique properties such as
cost-effectiveness, thickness uniformity, good wear resistance,
lubricity, good ductility and corrosion resistance, excellent
solderability and electrical properties and antibacterial property. In
this study, electroless Ni-B coating could been deposited on AZ91
magnesium alloy. The obtained coating exhibited a harder and
rougher structure than the substrate.
Abstract: Kurtbogazi Dam has gained special meaning for Ankara, Turkey for the last decade due to the rapid depletion of nearby resources of drinking water. In this study, the results of the analyses of Kurtbogazi Dam outlet water and the rivers flowing into the Kurtbogazi Dam were discussed for the period of last five years between 2008 and 2012. Some physical and chemical properties (pH, temperature, biochemical oxygen demand (BOD5), nitrate, phosphate and chlorine) of these water resources were evaluated. They were classified according to the Council Directive (75/440/EEC). Moreover, the properties of these surface waters were assessed to determine the quality of water for drinking and irrigation purposes using Piper, US Salinity Laboratory and Wilcox diagrams. The results showed that all the water resources are acceptable level as surface water except for Pazar Stream in terms of ortho-phosphate and BOD5 concentration for 2008.
Abstract: Underwater acoustic networks have attracted great
attention in the last few years because of its numerous applications.
High data rate can be achieved by efficiently modeling the physical
layer in the network protocol stack. In Acoustic medium,
propagation speed of the acoustic waves is dependent on many
parameters such as temperature, salinity, density, and depth.
Acoustic propagation speed cannot be modeled using standard
empirical formulas such as Urick and Thorp descriptions. In this
paper, we have modeled the acoustic channel using real time data of
temperature, salinity, and speed of Bay of Bengal (Indian Coastal
Region). We have modeled the acoustic channel by using Mackenzie
speed equation and real time data obtained from National Institute of
Oceanography and Technology. It is found that acoustic propagation
speed varies between 1503 m/s to 1544 m/s as temperature and
depth differs. The simulation results show that temperature, salinity,
depth plays major role in acoustic propagation and data rate
increases with appropriate data sets substituted in the simulated
model.
Abstract: Hypertension is a common condition causing cardio
and cerebrovascular complications. Portugal has one of the highest
mortality rates from stroke and a high prevalence of hypertension.
Systolic Blood Pressure (SBP) is an important risk factor for
cardiovascular events (myocardial infarction and stroke) and
premature mortality, particularly in the elderly population. The
present study aims to estimate the prevalence of hypertension in a
Portuguese population living in a coastal city and to identify some of
its determinants (namely gender, age, the body mass index and
physical activity frequency). A total of 91 adults who attended three pharmacies of a coastal
city in the center of Portugal, between May and August of 2013 were
evaluated. Attendants who reported to have diabetes or taking
antihypertensive drugs in the 2 previous weeks were excluded from
the study. Sociodemographic factors, BMI, habits of exercise and BP
were assessed. Hypertension was defined as blood pressure ≥140/90
mmHg. The majority of the studied population was constituted by women
(75.8%), with a mean age of 54.2±1.6 years old, married or living in
civil union and that had completed secondary school or had higher
education (40%). They presented a mean BMI of 26.2±4.76 Kg/m2.,
and were sedentary. The mean BP was 127.0±17.77mmHg- 74.69 ±
9.53. In this population we found 4.3% of people with hypertension
and 16.1% with normal high blood pressure. Men exhibit a tendency to present higher systolic blood pressure
values than women. Of all the factors considered, SBP values also
tended to be higher with age and higher BMI values.
Despite the fact that the mean values of SBP did not present values
higher than 140 mmHg we must be concerned because the studied
population is undiagnosed for hypertension. Although this is a preliminary study, it might be a prelude to the
upcoming research about the underlying factors responsible for the
occurrence of SBP.
Abstract: The critical concern of satellite operations is to ensure
the health and safety of satellites. The worst case in this perspective
is probably the loss of a mission, but the more common interruption
of satellite functionality can result in compromised mission
objectives. All the data acquiring from the spacecraft are known as
Telemetry (TM), which contains the wealth information related to the
health of all its subsystems. Each single item of information is
contained in a telemetry parameter, which represents a time-variant
property (i.e. a status or a measurement) to be checked. As a
consequence, there is a continuous improvement of TM monitoring
systems to reduce the time required to respond to changes in a
satellite's state of health. A fast conception of the current state of the
satellite is thus very important to respond to occurring failures.
Statistical multivariate latent techniques are one of the vital learning
tools that are used to tackle the problem above coherently.
Information extraction from such rich data sources using advanced
statistical methodologies is a challenging task due to the massive
volume of data. To solve this problem, in this paper, we present a
proposed unsupervised learning algorithm based on Principle
Component Analysis (PCA) technique. The algorithm is particularly
applied on an actual remote sensing spacecraft. Data from the
Attitude Determination and Control System (ADCS) was acquired
under two operation conditions: normal and faulty states. The models
were built and tested under these conditions, and the results show that
the algorithm could successfully differentiate between these
operations conditions. Furthermore, the algorithm provides
competent information in prediction as well as adding more insight
and physical interpretation to the ADCS operation.
Abstract: Hydrogels are three-dimensional, hydrophilic,
polymeric networks composed of homopolymers or copolymers and
are insoluble in water due to the presence of chemical or physical
cross-links. When hydrogels come in contact with aqueous solutions,
they can effectively sorb and retain the dissolved substances,
depending on the nature of the monomeric units comprising the
hydrogel. For this reason, hydrogels have been proposed in several
studies as water purification agents. At the present work anionic
hydrogels bearing negatively charged –COO- groups were prepared
and investigated. These gels are based on sodium acrylate (ANa),
either homopolymerized (poly(sodiumacrylate), PANa) or
copolymerized (P(DMAM-co-ANa)) with N,N Dimethylacrylamide
(DMAM). The hydrogels were used to extract some model organic
dyes from water. It is found that cationic dyes are strongly sorbed and
retained by the hydrogels, while sorption of anionic dyes was
negligible. In all cases it was found that both maximum sorption
capacity and equilibrium binding constant varied from one dye to the
other depending on the chemical structure of the dye, the presence of
functional chemical groups and the hydrophobic-hydrophilic balance.
Finally, the nonionic hydrogel of the homopolymer poly(N,Ndimethylacrylamide),
PDMAM, was also used for reasons of
comparison.
Abstract: This paper presents the advantages of fuzzy control use in technological processes control. The paper presents a real application of the Linguistic Fuzzy-Logic Control, developed at the University of Ostrava for the control of physical models in the Intelligent Systems Laboratory. The paper presents an example of a sensitive non-linear model, such as a magnetic levitation model and obtained results which show how modern information technologies can help to solve actual technical problems. A special method based on the LFLC controller with partial components is presented in this paper followed by the method of automatic context change, which is very helpful to achieve more accurate control results. The main advantage of the used system is its robustness in changing conditions demonstrated by comparing with conventional PID controller. This technology and real models are also used as a background for problem-oriented teaching, realized at the department for master students and their collaborative as well as individual final projects.
Abstract: Revenue leakages are one of the major challenges
manufacturers face in production processes, as most of the input
materials that should emanate as products from the lines are lost as
waste. Rather than generating income from material input which is
meant to end-up as products, losses are further incurred as costs in
order to manage waste generated. In addition, due to the lack of a
clear view of the flow of resources on the lines from input to output
stage, acquiring information on the true cost of waste generated have
become a challenge. This has therefore given birth to the
conceptualization and implementation of waste minimization
strategies by several manufacturing industries. This paper reviews the
principles and applications of three environmental management
accounting tools namely Activity-based Costing (ABC), Life-Cycle
Assessment (LCA) and Material Flow Cost Accounting (MFCA) in
the manufacturing industry and their effectiveness in curbing revenue
leakages. The paper unveils the strengths and limitations of each of
the tools; beaming a searchlight on the tool that could allow for
optimal resource utilization, transparency in production process as
well as improved cost efficiency. Findings from this review reveal
that MFCA may offer superior advantages with regards to the
provision of more detailed information (both in physical and
monetary terms) on the flow of material inputs throughout the
production process compared to the other environmental accounting
tools. This paper therefore makes a case for the adoption of MFCA as
a viable technique for the identification and reduction of waste in
production processes, and also for effective decision making by
production managers, financial advisors and other relevant
stakeholders.
Abstract: In this numerical study, effects of using Al2O3-water
nanofluid on the rate of heat transfer have been investigated. Physical
model is a square enclosure with insulated top and bottom horizontal
walls, while the vertical walls are kept at different constant
temperatures. Two appropriate models are used to evaluate the
viscosity and thermal conductivity of nanofluid. The governing
stream-vorticity equations are solved using a second order central
finite difference scheme, coupled to the conservation of mass and
energy. The study has been carried out for the nanoparticle diameter
30, 60 and 90 nm and the solid volume fraction 0 to 0.04. Results are
presented by average Nusselt number and normalized Nusselt number
in different range of φ and D for mixed convection dominated
regime. It is found that different heat transfer rate is predicted when
the effect of nanoparticle diameter is taken into account.
Abstract: Nowadays, the reflection on competence management
is the basic for new competitive strategies. It is considered as the core
of the problems of the global supply chain. It interact a variety of
actors: information, physical and activities flows, etc. Even though
competence management is seen as the key factor for any business
success, the existing approaches demonstrate the deficiencies and
limitations of the competence concept. This research has two
objectives: The first is to make a contribution by focusing on the
development of a competence approach, based on continuous
improvement. It allows the enterprise to spot key competencies,
mobilize them in order to serve its strategic objectives and to develop
future competencies. The second is to propose a method to evaluate
the Level of Collective Competence. The approach was confirmed
through an application carried out at an automotive company.
Abstract: This study was conducted to investigate the extent
with which knowledge of results influences the performance of
cricket players. A sample of 160 fresh students in the Department of
Physical and Health Education who are novice in the game were
randomly assigned into two groups. The first group of eighty (80)
subjects was classified as experimental group while the second group
of eighty (80) subjects was the control group. Subjects in both groups
were asked to bowl and bat ten times each for a period of six weeks.
After the first round, the subjects in the experimental group were
allowed feedback on their performance in the first trial while those in
the control group were denied feedback. Two null hypotheses
generated for the study were tested using percentages and chi-square
statistical analysis at 0.05 level of significance. Analysis of data
showed that knowledge of results influenced the performance of
cricket players. It was concluded that knowledge of results is
pertinent for effective skill acquisition and could enhance better
performance among unskilled cricket players. Hence, it is suggested
that immediate feedback on the level of skill acquisition by the
prospective and unskilled cricket players would inspire them for
better performance in cricket tournaments.
Abstract: Polylactic acid (PLA) is the most commercially
available bio-based and biodegradable plastic at present. PLA has
been used in plastic related industries including single-used
containers, disposable and environmentally friendly packaging owing
to its renewability, compostability, biodegradability, and safety.
Although PLA demonstrates reasonably good optical, physical,
mechanical and barrier properties comparable to the existing
petroleum-based plastics, its brittleness and mold shrinkage as well as
its price are the points to be concerned for the production of rigid and
semi-rigid packaging. Blending PLA with other bio-based polymers
including thermoplastic starch (TPS) is an alternative not only to
achieve a complete bio-based plastic, but also to reduce the
brittleness, shrinkage during molding and production cost of the
PLA-based products. TPS is a material produced mainly from starch
which is cheap, renewable, biodegradable, compostable, and nontoxic.
It is commonly prepared by a plasticization of starch under
applying heat and shear force. Although glycerol has been reported as
one of the most plasticizers used for preparing TPS, its migration
caused the surface stickiness of the TPS products. In some cases,
mixed plasticizers or natural fibers have been applied to impede the
retrogradation of starch or reduce the migration of glycerol. The
introduction of fibers into TPS-based materials could reinforce the
polymer matrix as well. Therefore, the objective of the present
research is to study the effect of starch type (i.e. native starch and
phosphate starch), plasticizer type (i.e. glycerol and xylitol with a
weight ratio of glycerol to xylitol of 100:0, 75:25, 50:50, 25:75 and
0:100) and fiber content (i.e. in the range of 1-25 %wt) on properties
of PLA/TPS blend and composite. PLA/TPS blends and composites
were prepared using a twin-screw extruder and then converted into
dumbbell-shaped specimens using an injection molding machine. The
PLA/TPS blends prepared by using phosphate starch showed higher
tensile strength and stiffness than the blends prepared by using native
one. In contrast, the blends from native starch exhibited higher
extensibility and heat distortion temperature (HDT) than those from
the modified starch. Increasing xylitol content resulted in enhanced
tensile strength, stiffness and water resistance, but decreased
extensibility and HDT of the PLA/TPS blend. Tensile properties and
hydrophobicity of the blend could be improved by incorporating
silane treated-jute fibers.
Abstract: The development of composite materials and the
related design and manufacturing technologies is one of the most
important advances in the history of materials. Composites are
multifunctional materials having unprecedented mechanical and
physical properties that can be tailored to meet the requirements of a
particular application. Some composites also exhibit great resistance
to high-temperature corrosion, oxidation, and wear. Polymers are
widely used indoors and outdoors, therefore they are exposed to a
chemical environment which may include atmospheric oxygen, acidic
fumes, acidic rain, moisture heat and thermal shock, ultra-violet light,
high energy radiation, etc. Different polymers are affected differently
by these factors even though the amorphous polymers are more
sensitive. Ageing is also important and it is defined as the process of
deterioration of engineering materials resulting from the combined
effects of atmospheric radiation, heat, oxygen, water, microorganisms
and other atmospheric factors.
Abstract: Rapid prototyping is a new group of manufacturing
processes, which allows fabrication of physical of any complexity
using a layer by layer deposition technique directly from a computer
system. The rapid prototyping process greatly reduces the time and
cost necessary to bring a new product to market. The prototypes
made by these systems are used in a range of industrial application
including design evaluation, verification, testing, and as patterns for
casting processes. These processes employ a variety of materials and
mechanisms to build up the layers to build the part. The present work
was to build a FDM prototyping machine that could control the X-Y
motion and material deposition, to generate two-dimensional and
three-dimensional complex shapes. This study focused on the
deposition of wax material. This work was to find out the properties
of the wax materials used in this work in order to enable better
control of the FDM process. This study will look at the integration of
a computer controlled electro-mechanical system with the traditional
FDM additive prototyping process. The characteristics of the wax
were also analysed in order to optimise the model production process.
These included wax phase change temperature, wax viscosity and
wax droplet shape during processing.
Abstract: This study aims at improving the urban hydrological
cycle of the Orléans agglomeration (France) and understanding the
relationship between physical and chemical parameters of urban
surface runoff and the hydrological conditions. In particular water
quality parameters such as pH, conductivity, total dissolved solids,
major dissolved cations and anions, and chemical and biological
oxygen demands were monitored for three types of urban water
discharges (wastewater treatment plant output (WWTP), storm
overflow and stormwater outfall) under two hydrologic scenarios (dry
and wet weather). The first results were obtained over a period of five
months. Each investigated (Ormes, l’Egoutier and La Corne) outfall
represents an urban runoff source that receives water from runoff
roads, gutters, the irrigation of gardens and other sources of flow over
the Earth’s surface that drains in its catchments and carries it to the
Loire River. In wet weather conditions there is rain water runoff and
an additional input from the roof gutters that have entered the
stormwater system during rainfall. For the comparison the results La
Chilesse is a storm overflow that was selected in our study as a
potential source of waste water which is located before the (WWTP). The comparison of the physical-chemical parameters (total
dissolved solids, turbidity, pH, conductivity, dissolved organic
carbon (DOC), concentration of major cations and anions) together
with the chemical oxygen demand (COD) and biological oxygen
demand (BOD) helped to characterize sources of runoff waters in the
different watersheds. It also helped to highlight the infiltration of
wastewater in some stormwater systems that reject directly in the
Loire River. The values of the conductivity measured in the outflow
of Ormes were always higher than those measured in the other two
outlets. The results showed a temporal variation for the Ormes outfall
of conductivity from 1465 μS cm-1 in the dry weather flow to 650 μS
cm-1 in the wet weather flow and also a spatial variation in the wet
weather flow from 650 μS cm-1 in the Ormes outfall to 281 μS cm-1
in L’Egouttier outfall. The ultimate BOD (BOD28) showed a
significant decrease in La Corne outfall from 181 mg L-1 in the wet
weather flow to 95 mg L-1 in the dry weather flow because of the
nutrient load that was transported by the runoff.
Abstract: Rice Husk (RH) is the major byproduct in the
processing of paddy rice. The management of this waste has become
a big challenge to some of the rice producers, some of these wastes
are left in open dumps while some are burn in the open space, and
these two actions have been contributing to environmental pollution.
This study evaluates an alternative waste management of this
agricultural product for use as a civil engineering material. The RH
was burn in a controlled environment to form Rice Husk Ash (RHA).
The RHA was mix with lateritic clay at 0, 2, 4, 6, 8, and 10%
proportion by weight. Chemical test was conducted on the open burn
and controlled burn RHA with the lateritic clay. Physical test such as
particle size distribution, Atterberg limits test, and density test were
carried out on the mix material. The chemical composition obtained
for the RHA showed that the total percentage compositions of Fe2O3,
SiO2 and Al2O3 were found to be above 70% (class “F” pozzolan)
which qualifies it as a very good pozzolan. The coefficient of
uniformity (Cu) was 8 and coefficient of curvature (Cc) was 2 for the
soil sample. The Plasticity Index (PI) for the 0, 2, 4, 6, 8. 10% was
21.0, 18.8, 16.7, 14.4, 12.4 and 10.7 respectively. The work
concluded that RHA can be effectively used in hydraulic barriers and
as a stabilizing agent in soil stabilization.
Abstract: The purpose of this theoretical literature review is to
study the relevant academic literature on lack of cardiorespiratory
fitness and its effects on children. The total of thirty eight relevant
documents were identified and considered for this review which
nineteen of those were original research articles published in peer
reviewed journals. The other nineteen articles were statistical
documents. This literature review is structured to examine 5 effects
in deficiency of cardiorespiratory fitness in school aged children (A)
Relative Age Effect (RAE), (B) Obesity, (C) Inadequate fitness level
(D) Unhealthy life style, and (E) Academics. The categories provide
a theoretical framework for future studies where results are driven
from the literature review. The study discusses that regular physical fitness assists children
and adolescents to develop healthy physical activity behaviors which
can be sustained throughout adult life. Conclusion suggests that
advocacy for increasing physical activity and decreasing sedentary
behaviors at school and home are necessary.
Abstract: High moisture content in fruits generates post-harvest
problems such as mechanical, biochemical, microbial and physical
losses. Dehydration, which is based on the reduction of water activity
of the fruit, is a common option for overcoming such losses.
However, regular hot air drying could affect negatively the quality
properties of the fruit due to the long residence time at high
temperature. Power ultrasound (US) application during the
convective drying has been used as a novel method able to enhance
drying rate and, consequently, to decrease drying time. In the present
study, a new approach was tested to evaluate the effect of US on the
drying time, the final antioxidant activity (AA) and the total
polyphenol content (TPC) of banana slices (BS), mango slices (MS)
and guava slices (GS). There were also studied the drying kinetics
with nine different models from which water effective diffusivities
(Deff) (with or without shrinkage corrections) were calculated.
Compared with the corresponding control tests, US assisted drying
for fruit slices showed reductions in drying time between 16.23 and
30.19%, 11.34 and 32.73%, and 19.25 and 47.51% for the MS, BS
and GS respectively. Considering shrinkage effects, Deff calculated
values ranged from 1.67*10-10 to 3.18*10-10 m2/s, 3.96*10-10 and
5.57*10-10 m2/s and 4.61*10-10 to 8.16*10-10 m2/s for the BS, MS and
GS samples respectively. Reductions of TPC and AA (as DPPH)
were observed compared with the original content in fresh fruit data
in all kinds of drying assays.
Abstract: The Radio Frequency Identification (RFID) technology
has a diverse base of applications, but it is also prone to security
threats. There are different types of security attacks which limit the
range of the RFID applications. For example, deploying the RFID
networks in insecure environments could make the RFID system
vulnerable to many types of attacks such as spoofing attack, location
traceability attack, physical attack and many more. Therefore, security
is often an important requirement for RFID systems. In this paper,
RFID mutual authentication protocol is implemented based on mobile
agent technology and timestamp, which are used to provide strong
authentication and integrity assurances to both the RFID readers and
their corresponding RFID tags. The integration of mobile agent
technology and timestamp provides promising results towards
achieving this goal and towards reducing the security threats in RFID
systems.
Abstract: Si-Ge solid solutions (bulk poly- and mono-crystalline
samples, thin films) are characterized by high perspectives for
application in semiconductor devices, in particular, optoelectronics
and microelectronics. From this point of view, complex studying of
structural state of the defects and structural-sensitive physical
properties of Si-Ge solid solutions depending on the contents of Si
and Ge components is very important. Present work deals with the
investigations of microstructure, microhardness, internal friction and
shear modulus of Si1-xGex(x≤0,02) bulk monocrystals conducted at
room temperature. Si-Ge bulk crystals were obtained by Czochralski
method in [111] crystallographic direction. Investigated
monocrystalline Si-Ge samples are characterized by p-type
conductivity and carriers’ concentration 5.1014-1.1015cm-3.
Microhardness was studied on Dynamic Ultra Micro hardness Tester
DUH-201S with Berkovich indenter. Investigate samples are characterized with 0,5x0,5x(10-15)mm3
sizes, oriented along [111] direction at torsion oscillations ≈1Hz,
multistage changing of internal friction and shear modulus has been
revealed in an interval of strain amplitude of 10-5-5.10-3. Critical
values of strain amplitude have been determined at which hysteretic
changes of inelastic characteristics and microplasticity are observed. The critical strain amplitude and elasticity limit values are also
determined. Dynamic mechanical characteristics decreasing trend is
shown with increasing Ge content in Si-Ge solid solutions. Observed
changes are discussed from the point of view of interaction of various
dislocations with point defects and their complexes in a real structure
of Si-Ge solid solutions.